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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4a0cefbed3e4e4f9c01b3978101ba7563e62edbc2187ccfc168c1a86c6d5f218' 
  AND token = 'oaOvOnNqau/VV8dmhv0gmp8pY4D4Zgrw45k3NTzs1xE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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