SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3b2b9d825c6b50d8cb678a465c004b1826303728f34a834e3fb008cf822c946' 
  AND token = 'tJbp3mtuqmffZb8gxK34l4TrWCzrSh864ULfVMUOT8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}