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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'eb28a21f5c8fc07d4a4ed14b4cddd90e4dd37b2e8f121331de358b9f52cd3781' 
  AND token = 'EjUsa59n+08h+Vh4UUr1bQ8nkLD+F5plUJ+tNTSmqT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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