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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fbc2ce6850dd6a8ab20cf4d753a3fd1f24759d17b3ab6366ec5787dd079f8c3c' 
  AND token = 'r1aYZ82fytHgaazVOcZqMh+CrTEiK9CtrliDQyhshhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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