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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a8420feb41c97771b506fa552a0aeaf9b079b15ff256be36978a7e7a73ea7fa8' 
  AND token = 'hJwQMKi+fcf7lMreslo1+NL5/8RQ+Ca4gTZhKQTJFwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}