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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cbcdfb8676912bec6a701509b55c2c6795d22bac2ab9f706dda7711b7100b82c' 
  AND token = 'ext1Ow+Icw0M3s91jpO59rccn9cSif3Op4MwhUfYm4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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